Widely applied to various electronic products, a DC-to-DC converter provides the functions of regulating the voltage level from a DC input voltage, such as boost or buck voltage conversion, and of maintaining the regulated voltage at the desired level. For example, in a computer system, due to the power supplies of different voltages for CPU, memory and hard disk drive, the DC-to-DC converter is required to regulate the power source voltage of the computer system to various supply voltages supplied to various operational units of the computer system.
Typically, a DC-to-DC converter modulates the duty cycle of an output stage by a driving signal, to thereby regulate the output voltage of the converter within a demanded range. In a conventional DC-to-DC converter, the output voltage of the converter is detected to generate a feedback signal, which feedback signal is compared with a threshold signal by an error amplifier to generate an error signal for a pulse width modulation (PWM) comparator to compare with a ramp signal to generate a PWM signal, and the PWM signal is supplied to a driver to drive the output stage. In this converter, an oscillator is generally employed to generate the ramp signal for the PWM comparator, so as to modulate the duty cycle of the PWM signal.
Alternatively, it is desired a DC-to-DC converter and method thereof based on a different operational principle.